Some help with this pleaseee!

Abike shop sells you a bicycle for $63 and a helmet for $21. the total cost is 150% of what the shop spent originally. how much did the shop spend originally? how much profit did the bike shop earn by selling the bicycle and helmet to you ?

What is the domain of the step function f(x)=[2x]-1?

Ofof is a ? a. (1, 2), (1,-2), (3, 2), (3, 4) b. (1,6), (2, ,9), (0,5) c. (0, 2), (2,3), (0, -2), (4,1) d. (2, 4), (0, 2), (2, - 4), (5,3)